Tracing the s± symmetry in iron pnictides by controlled disorder

M. B. Schilling, A. Baumgartner, B. Gorshunov, E. S. Zhukova, V. A. Dravin, K. V. Mitsen, D. V. Efremov, O. V. Dolgov, K. Iida, M. Dressel, and S. Zapf
Phys. Rev. B 93, 174515 – Published 24 May 2016
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Abstract

Determining the symmetry of the superconducting order parameter is the most important but also the most complicated step in elucidating the mechanism of superconductivity. Here we present an experimental approach to investigate the order parameter symmetry of unconventional multiband superconductors, which is based on a disorder-induced change from sign-reversed (s±) to sign-preserved (s++) symmetry. Therefore, we investigated a Ba(Fe0.9Co0.1)2As2 thin film by THz spectroscopy and stepwise proton irradiation. In our experiments, the low-energy superconducting gap first vanishes but recovers at higher irradiation doses. At the same time, the decrease of the superfluid density with disorder comes to a halt. Thus, we confirm with the method presented here that the superconducting order parameter in the pristine sample possesses s± symmetry.

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  • Received 12 December 2015
  • Revised 26 April 2016

DOI:https://doi.org/10.1103/PhysRevB.93.174515

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

M. B. Schilling1,*, A. Baumgartner1, B. Gorshunov1,2,3, E. S. Zhukova1,2,3, V. A. Dravin4, K. V. Mitsen4, D. V. Efremov5, O. V. Dolgov6,4, K. Iida7,8, M. Dressel1, and S. Zapf1

  • 11. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
  • 2A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, 119991 Moscow, Russia
  • 3Moscow Institute of Physics and Technology (State University), 141700, Dolgoprudny, Moscow Region, Russia
  • 4P. N. Lebedev Physical Institute, Moscow, 119991 Russia
  • 5Institute for Theoretical Solid State Physics, IFW Dresden, Germany
  • 6Max-Planck Institut für Festkörperforschung, 70569 Stuttgart, Germany
  • 7Institute for Metallic Materials, IFW Dresden, Germany
  • 8Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan

  • *micha.schilling@pi1.physik.uni-stuttgart.de

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Issue

Vol. 93, Iss. 17 — 1 May 2016

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